U.S. patent application number 12/891401 was filed with the patent office on 2011-06-16 for imaging method for microcalcification in tissue and imaging method for diagnosing breast cancer.
Invention is credited to Shin-Cheh CHEN, Yao-Yu CHENG, Chih-Tai FAN, Tsai-Chu HSIAO, Meng-Lin LI, Po-Hsun WANG.
Application Number | 20110144496 12/891401 |
Document ID | / |
Family ID | 44143719 |
Filed Date | 2011-06-16 |
United States Patent
Application |
20110144496 |
Kind Code |
A1 |
LI; Meng-Lin ; et
al. |
June 16, 2011 |
IMAGING METHOD FOR MICROCALCIFICATION IN TISSUE AND IMAGING METHOD
FOR DIAGNOSING BREAST CANCER
Abstract
An imaging method for microcalcification displays
microcalcification distribution by acquiring and overlapping a
photoacoustic image of microcalcification and an ultrasonic image
of tissue. The image acquired by the present invention, in
comparison to images acquired by ultrasonic and X-ray mammography,
has advantages in no speckle noises, higher optical contrast,
higher ultrasonic resolution, and so on. The present invention also
has advantage in safety by adopting a light source having no
ionizing radiation. An imaging method for diagnosing breast cancer
is also herein disclosed.
Inventors: |
LI; Meng-Lin; (Hsinchu,
TW) ; HSIAO; Tsai-Chu; (Hsinchu, TW) ; CHEN;
Shin-Cheh; (Hsinchu, TW) ; CHENG; Yao-Yu;
(Kaohsiung City, TW) ; WANG; Po-Hsun; (Kaohsiung
City, TW) ; FAN; Chih-Tai; (Taipei City, TW) |
Family ID: |
44143719 |
Appl. No.: |
12/891401 |
Filed: |
September 27, 2010 |
Current U.S.
Class: |
600/443 |
Current CPC
Class: |
A61B 5/0095 20130101;
A61B 5/0091 20130101; A61B 8/06 20130101; A61B 8/5238 20130101;
A61B 8/13 20130101; A61B 5/7425 20130101; A61B 8/0825 20130101 |
Class at
Publication: |
600/443 |
International
Class: |
A61B 8/14 20060101
A61B008/14 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2009 |
TW |
098142816 |
Claims
1. An imaging method for microcalcification in tissue, comprising:
emitting a first ultrasound to a tissue; receiving an echo wave of
the first ultrasound and forming a first ultrasound image of the
tissue; emitting a first light to the tissue to induce a first
photoacoustic ultrasound; receiving the first photoacoustic
ultrasound and forming a first photoacoustic image of a
microcalcification; and superimposing the first ultrasound image
and the first photoacoustic image to form a first superimposed
image for illustrating the microcalcification distributed within
the tissue.
2. The imaging method as claimed in claim 1, wherein the light is a
laser beam.
3. The imaging method as claimed in claim 2, wherein the laser beam
has a wavelength in the range of 3200 nm to 3600 nm.
4. The imaging method as claimed in claim 2, wherein the laser beam
has a wavelength in the range of 700 nm to 1200 nm.
5. The imaging method as claimed in claim 2, wherein the laser beam
has a wavelength in the range of 700 nm to 850 nm.
6. The imaging method as claimed in claim 1, wherein the first
ultrasound image comprises a 2D ultrasound image, a 3D ultrasound
image or a Doppler ultrasound image.
7. The imaging method as claimed in claim 1, wherein the first
photoacoustic image comprises a 2D ultrasound image or a 3D
ultrasound image.
8. The imaging method as claimed in claim 1, wherein the first
photoacoustic image is formed with backward mode, forward mode or
tomography mode.
9. The imaging method as claimed in claim 1, wherein the
microcalcification comprises calcium oxalate, calcium
hydroxyapatite, calcium carbonate hydroxyapatite or the
combinations thereof.
10. The imaging method as claimed in claim 1, wherein the tissue
comprises breast, blood vessel, lung, thyroid or kidney.
11. The imaging method as claimed in claim 1, further comprising:
projecting the first photoacoustic image or the first superimposed
image to obtain a 2D projecting image, wherein the first
photoacoustic image or the first superimposed image is
3-Dimensional.
12. The imaging method as claimed in claim 1, wherein the first
photoacoustic image is obtained along a projection line of an X-ray
photography.
13. The imaging method as claimed in claim 1 further comprising:
emitting a second ultrasound to the tissue; receiving an echo wave
of the second ultrasound and forming a second ultrasound image of
the tissue; emitting a second light to the tissue to induce a
second photoacoustic ultrasound; receiving the second photoacoustic
ultrasound and forming a second photoacoustic image of a
microcalcification; and superimposing the second ultrasound image
and the second photoacoustic image to form a second superimposed
image, wherein a frame of the first photoacoustic image is formed
between a frame of the first ultrasound and a frame of the second
ultrasound.
14. An imaging method for diagnosing breast cancer, comprising:
emitting a first ultrasound to a breast tissue; receiving an echo
wave of the first ultrasound and forming a first ultrasound image
of the breast tissue; emitting a first light to the breast tissue
to induce a first photoacoustic ultrasound; receiving the first
photoacoustic ultrasound and forming a first photoacoustic image of
a microcalcification; and superimposing the first ultrasound image
and the first photoacoustic image to form a first superimposed
image for illustrating the microcalcification distributed within
the breast tissue and diagnosing the phase and stage of breast
cancer.
15. The imaging method as claimed in claim 14, wherein the light is
a laser beam.
16. The imaging method as claimed in claim 15, wherein the laser
beam has a wavelength in the range of 3200 nm to 3600 nm.
17. The imaging method as claimed in claim 15, wherein the laser
beam has a wavelength in the range of 700 nm to 1200 nm.
18. The imaging method as claimed in claim 15, wherein the laser
beam has a wavelength in the range of 700 nm to 850 nm.
19. The imaging method as claimed in claim 14, wherein the first
ultrasound image comprises a 2D ultrasound image, a 3D ultrasound
image or a Doppler ultrasound image.
20. The imaging method as claimed in claim 14, wherein the first
photoacoustic image comprises a 2D ultrasound image or a 3D
ultrasound image.
21. The imaging method as claimed in claim 14, wherein the first
photoacoustic image is formed with backward mode, forward mode or
tomography mode.
22. The imaging method as claimed in claim 14, wherein the
microcalcification comprises calcium oxalate, calcium
hydroxyapatite, calcium carbonate hydroxyapatite or the
combinations thereof.
23. The imaging method as claimed in claim 14, further comprising:
projecting the first photoacoustic image or the first superimposed
image to obtain a 2D projecting image, wherein the first
photoacoustic image or the first superimposed image is
3-Dimensional.
24. The imaging method as claimed in claim 14, wherein the first
photoacoustic image is obtained along a projection line of an X-ray
photography.
25. The imaging method as claimed in claim 14, wherein the phase
and stage of breast cancer is diagnosed via density distribution,
shape or composition of the microcalcification.
26. The imaging method as claimed in claim 14 further comprising:
emitting a second ultrasound to the breast tissue; receiving an
echo wave of the second ultrasound and forming a second ultrasound
image of the breast tissue; emitting a second light to the breast
tissue to induce a second photoacoustic ultrasound; receiving the
second photoacoustic ultrasound and forming a second photoacoustic
image of a microcalcification; and superimposing the second
ultrasound image and the second photoacoustic image to form a
second superimposed image, wherein a frame of the first
photoacoustic image is formed between a frame of the first
ultrasound and a frame of the second ultrasound.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an imaging method for
microcalcification in tissue and imaging method for diagnosing
breast cancer, particularly to an imaging method for
microcalcification in tissue and imaging method for diagnosing
breast cancer by acquiring and superimposing a photoacoustic image
of microcalcification and an ultrasonic image of tissue.
[0003] 2. Description of the Prior Art
[0004] Microcalcification in breast has been one of the important
indicators for early diagnosis for breast cancer and the location
and distribution of microcalcification is also an important
indicator for distinguishing malignant breast tumor. Therefore,
detection of microcalcification in the breast is important for
early diagnosis of breast tumor. X-ray mammogram is the most
economical and effective screening tool among all and the only
approved screening tool for breast cancer in many countries,
including the United States, around the world. X-ray mammogram has
been provided with high sensitivity for breast microcalcification
and most microcalcification may be clearly observed in the X-ray
film.
[0005] However, the X-ray mammogram may display microcalcification
but not other subtle structures, such as mammary ducts. The result
of X-ray mammogram for a patient can not be directly interpreted by
radiologists and a further ultrasound test is needed to be
performed by doctors. However, due to speckle noises present in the
ultrasound image and relative low contrast between the breast
tissue and microcalcification, the sensitivity of the
microcalcification image is less than 30%. Therefore, it has been a
huge challenge for all clinical practitioners to find out the
position of suspected tumor and microcalcification found in X-ray
mammogram using an ultrasound system.
[0006] In addition, photoacoustic imaging has been used for breast
cancer screening. Photoacoustic imaging or photoacoustic tomography
(PAT) is performed by using laser to induce ultrasound and has
advantages in high contrast of optical imaging as well as the high
penetration depth and high resolution of ultrasound. The
photoacoustic imaging may choose various wavelengths for the light
source based on the absorption spectrum feature to obtain images
for various tissues. However, the photoacoustic imaging used for
screening the breast cancer is mainly focused on blood objects,
such as angiogenesis and hemorrhagic infiltration.
[0007] To sum up, it is now a current goal to develop an effective
screening method for breast microcalcification.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to an imaging method for
microcalcification which displays microcalcification distribution
by acquiring and overlapping a photoacoustic image of
microcalcification and an ultrasonic image of tissue. The image
acquired by the present invention, in comparison to images acquired
by ultrasonic and X-ray mammography, has advantages in no speckle
noises, higher optical contrast, higher ultrasonic resolution, and
so on.
[0009] In one embodiment, an imaging method for microcalcification
in tissue including emitting a first ultrasound to a tissue;
receiving an echo wave of the first ultrasound and forming a first
ultrasound image of the tissue; emitting a first light to the
tissue to induce a first photoacoustic ultrasound; receiving the
first photoacoustic ultrasound and forming a first photoacoustic
image of a microcalcification; and superimposing the first
ultrasound image and the first photoacoustic image to form a first
superimposed image for illustrating the microcalcification
distributed within the tissue.
[0010] The present invention is also directed to an imaging method
for diagnosing breast cancer, which displays microcalcification in
the breast to analyze the stage and phase of the breast cancer. The
present invention adopts a light source having no ionizing
radiation and thus has an advantage in safety.
[0011] In another embodiment, an imaging method for diagnosing
breast cancer includes emitting a first ultrasound to a breast
tissue; receiving an echo wave of the first ultrasound and forming
a first ultrasound image of the breast tissue; emitting a first
light to the tissue to induce a first photoacoustic ultrasound;
receiving the first photoacoustic ultrasound and forming a first
photoacoustic image of a microcalcification; and superimposing the
first ultrasound image and the first photoacoustic image to form a
first superimposed image for illustrating the microcalcification
distributed within the breast tissue and diagnosing the phase and
stage of breast cancer.
[0012] Other advantages of the present invention will become
apparent from the following descriptions taken in conjunction with
the accompanying drawings wherein certain embodiments of the
present invention are set forth by way of illustration and
examples.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The patent or application file contains at least one drawing
executed in color. Copies of this patent application publication
with color drawing(s) will be provided by the Office upon request
and payment of the necessary fee.
[0014] The foregoing aspects and many of the accompanying
advantages of this invention will become more readily appreciated
as the same becomes better understood by reference to the following
detailed descriptions, when taken in conjunction with the
accompanying drawings, wherein:
[0015] FIG. 1 is a flow chart illustrating an imaging method for
microcalcification according to an embodiment of the present
invention;
[0016] FIG. 2 is a schematic diagram illustrating an integrated
system of photoacoustic imaging and ultrasound imaging according to
an embodiment of the present invention;
[0017] FIGS. 3a-3b are diagrams illustrating the preferred infrared
wavelength according to one embodiment of the present
invention;
[0018] FIG. 4 is a flow chart illustrating a diagnostic method for
breast cancer according to one embodiment of the present
invention;
[0019] FIG. 5 is an ultrasound image of the mock tissue according
to an embodiment of the present invention;
[0020] FIG. 6 is a photoacoustic ultrasound image according to an
embodiment of the present invention; and
[0021] FIG. 7 is an imaging result illustrating the
microcalcification in the tissue according to one embodiment of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] The present invention is directed to a superimposed image
generated from a photoacoustic image of microcalcification on an
ultrasound image of the tissue. The superimposed image is used for
illustrating microcalcification distributed within the tissue.
[0023] Refer to FIG. 1 and FIG. 2, where FIG. 1 is a flow chart
illustrating an imaging method for microcalcification according to
an embodiment of the present invention, and FIG. 2 is a schematic
diagram illustrating an integrated system of photoacoustic imaging
and ultrasound imaging according to an embodiment of the present
invention.
[0024] First, Steps S11 and S12 are performed to obtain an
ultrasound image of ROI (Region of Interest) tissue. Step S11
includes emitting a first ultrasound to a tissue. The ultrasound
may be generated with an ultrasound array transducer 11. Short
electrical pulses generated with the ultrasound array transducer 11
result in the ultrasound at the desired frequency. The ultrasound
array transducer 11 may be integrated with a medical ultrasound
array imaging system 12. The ultrasound array transducer 11 having
desired frequency may be chosen based on resolution and penetrating
depth; for example, a transducer having a middle frequency such as
10 MHz may be chosen for 5 cm depth and 300 .mu.m resolution.
[0025] Step S12 includes receiving an echo wave of the first
ultrasound and forming a first ultrasound image of the ROI tissue.
The sound wave is effectively transmitted into the ROI tissue with
the assistance of the ultrasound array transducer 11 and partially
reflected from the layers between different tissues where density
changes occur in tissue, e.g. the interface between tumor cells and
normal cells within the tissue or the interface between the tissue
and the cysts. The partially reflected echo wave would return to
and oscillate the ultrasound array transducer 11 and be absorbed by
the ultrasound array transducer 11. The ultrasound array transducer
11 then converts the oscillation into electrical impulse signal,
which is received, amplified, modulated and displayed by the
ultrasound array imaging system 12.
[0026] Here, the common display modes adopted in medical field
include A mode (Amplitude Mode), B mode (Brightness Mode), M mode
(Motion Mode), D mode (Doppler Mode) and so on.
[0027] In addition, the first ultrasound image may be classified
into a 2D image, a 3D image or a Doppler image based on the imaging
theory of ultrasound. The 2D ultrasound image is a planar sectional
view displaying internal structures within the tissue for observing
the shape and size of structures. The 3D ultrasound image,
processed by a computer, is formed by recombining a series of
adjacent 2D ultrasound images with enhanced contrast and displaying
a three-dimensional ultrasound image on the screen. For real-time
3D ultrasound imaging, a two-dimensional array ultrasound
transducer is adopted for acquiring images in a 3-dimensional
manner to display 3D ultrasound image on the screen in a real-time
manner. For Doppler ultrasound imaging, Doppler Effect is applied
for resolving the blood flow rate and vessel distribution.
[0028] Step S13 and Step S14 are next performed to obtain a
photoacoustic image for microcalcification. Step S13 includes
emitting a first light, preferably a laser beam, to the ROI tissue
to induce a first photoacoustic ultrasound. As illustrated in FIG.
2, the laser beam emitted by the impulse laser system 21 is guided
to the linear optical guide array 24 through the lens 22 and beam
splitter 23 to scan the ROI tissue for obtaining photoacoustic
images. For photoacoustic imaging mode, the impulse laser system 21
and ultrasound array imaging system 12 may be synchronized by the
laser control unit 3. Therefore, the laser beam emitted from the
impulse laser system 21 may be triggered either by the ultrasound
array imaging system 12 or by the impulse laser system 21 itself
for photoacoustic imaging.
[0029] As above-mentioned, the light for photoacoustic imaging is a
laser beam, preferably. For example, the laser beam having tunable
wavelength may be generated by an optical parametric oscillator
driven by a Nd:YAG impulse laser. For example, the output laser may
have 3.about.20 ns in impulse width, 10 Hz.about.KHz in pulse
repetition frequency (PRF) and tunable 410.about.4000 nm in
wavelength. The weak focus of laser energy on the target is
achieved by using dark-field and is confocal with the elevational
direction of the ultrasound array transducer 11. Here, the dark
field is used for preventing interference caused by strong photon
absorption of surface, and the confocal configuration may enhance
SNR of images.
[0030] In addition, partial laser energy may be coupled into the
optical fiber used for monitoring laser energy. The output energy
guided by the optical fiber is monitored by LED and used for post
processing for eliminating instable output energy of the laser. The
above-mentioned configuration is not thus limited, however. Any
other configuration that adopts other laser radiation to the target
and monitors laser energy may be used as long as the aforesaid
function is achieved. Here, the energy density of the impulse laser
exposed to the tissue surface should be less than the allowable
maximum defined by ANSI.
[0031] Microcalcification has now been related to some acute or
chronic diseases, such as acute inflammation or tumor.
Microcalcification may be distributed in tissues, for example,
without limitation to breast, blood vessel, lung, thyroid or
kidney.
[0032] Microcalcification imaging is preferably achieved by using
near infrared light, having 700 nm.about.1200 nm wavelength.
Referring to FIG. 3a, cited from T. J. Brukilacchio, Ph.D. Thesis
2003, near infrared light has deeper penetration depth in tissue
and is less absorbed by the blood components such as hemoglobin
(Hb), oxygenated Hb, lipid and water. To be specific, the infrared
light having <700 nm wavelength is greatly absorbed by the
non-oxygenated Hb, and the infrared light having >900 nm is
greatly absorbed by the lipid; therefore, the 700-850 nm forms the
preferred optical window for breast tissue transmission. In
addition, referring to FIG. 3b, within the range of 700-850 nm, the
optical absorbance or photoacoustic signal for microcalcification
is greater in comparison to blood, lipid or gland tissue.
Therefore, the reading of a microcalcification image would be less
influenced by the blood, lipid, or gland signal.
[0033] In addition, the microcalcification in the breast has been
related to tumor malignancy in literature. The major composition of
mammary microcalcification includes calcium oxalate, calcium
hydroxyapatite, calcium carbonate hydroxyapatite or the
combinations thereof. Calcium oxalate is mainly present in
non-invasive tumors and calcium hydroxyapatite is mainly found in
invasive tumors. Particularly, the more phosphate is replaced by
carbonate in calcium carbonate hydroxyapatite, the higher
possibility the tumors are non-invasive. Due to absorbance
difference of calcium oxalate, calcium hydroxyapatite and calcium
carbonate hydroxyapatite in 3200 nm to 3600 nm, light source having
wavelength in 3200 nm to 3600 nm may used for photoacoustic imaging
of microcalcification characteristic absorbance spectrum so as to
qualitatively analyze microcalcification composition. The obtained
result may further be used for risk determination of ductal
carcinoma in situ and an objective basis for subsequent adoption of
positive treatment or conservative observation.
[0034] Step S14 includes receiving the first photoacoustic
ultrasound and forming a first photoacoustic image of the
microcalcification. The photoacoustic and ultrasound integrated
system may perform simultaneous capture for multi-array channel
signals. The signals are pre-amplified and converted to digital
signals by A/D converters. Beamforming of the ultrasound receive
beamformer and dynamic focusing are then performed to form
photoacoustic imaging. The above processing flow is the same as the
signal processing system of receiving end of present ultrasound
system. However, due to relative much faster speed of light
comparing to the speed of sound, the traveling time of laser beam
in the tissue may be neglected and only the time of photoacoustic
echo needs to be considered when calculating imaging depth.
[0035] It is noted that the photoacoustic and ultrasound integrated
system of the present invention may switch between the
photoacoustic mode and ultrasound imaging mode and may sequentially
and/or simultaneously capturing and displaying photoacoustic and
ultrasound images for verifying the relative position of
microcalcification.
[0036] Therefore, the formation of ultrasound and photoacoustic
images, in terms of first ultrasound image and first photoacoustic
image has no sequential limit.
[0037] In addition, the present invention may be used for forming
consecutive dynamic images obtained by similar steps as
above-mentioned, including emitting a second ultrasound to the
tissue; receiving an echo wave of the second ultrasound and forming
a second ultrasound image of the tissue; emitting a second light to
the tissue to induce a second photoacoustic ultrasound; receiving
the second photoacoustic ultrasound and forming a second
photoacoustic image of a microcalcification; and superimposing the
second ultrasound image and the second photoacoustic image to form
a second superimposed image. Preferably, a frame of the first
photoacoustic image is formed between a frame of the first
ultrasound and a frame of the second ultrasound. Since the
photoacoustic imaging frame is sandwiched between two sequential
B-mode pulse echo frames of ultrasound, the system of the present
invention has no difference from present medical ultrasound array
system in the way it is operated and remains using the operating
method of conventional ultrasound system without additional
scanning time for adding a photoacoustic image of the same
resolution as the ultrasound image.
[0038] As fore-mentioned, the first ultrasound image may be 2D
ultrasound images or 3D ultrasound images. The scanning method of
the first photoacoustic image which may be determined by the
positional configuration of the ultrasound array transducer 11 and
the linear optical guide array 24 includes backward mode, forward
mode and tomography mode. The first photoacoustic image may be 2D
ultrasound images or 3D ultrasound images as above-mentioned.
[0039] Finally, Step S15 includes superimposing the first
ultrasound image and the first photoacoustic image so as to form a
first superimposed image for illustrating microcalcification
distributed within the tissue (Step S16).
[0040] In one embodiment, the present invention provides a 2D
projection image similar to the X ray photography. As
fore-mentioned, X ray photography is the major detecting method at
present and a 2D image is obtained by projecting the test object
along a projection line. The 3D first photoacoustic image or the
first superimposed image may be projected to obtain a 2D projection
image so that the clinical practitioners may obtain projection
result similar to the X ray photography to replace and/or to
compare with standard mammary X ray photography.
[0041] As mentioned previously, microcalcification in breast is
known as one of the important indicators for early diagnosis of
breast cancer. FIG. 4 is a flow chart illustrating a diagnostic
method for breast cancer. Referring to FIG. 4, a diagnostic method
for breast cancer includes emitting a first ultrasound to a breast
tissue (Step S21); receiving an echo wave of the first ultrasound
and forming a first ultrasound image of the breast tissue (Step
S22); emitting a first light, preferably a laser beam to the breast
tissue to induce a first photoacoustic ultrasound (Step S23);
receiving the first photoacoustic ultrasound and forming a first
photoacoustic image of the microcalcification (Step S24); and
superimposing the first ultrasound image and the first
photoacoustic image to form a first superimposed image (Step 25);
illustrating microcalcification distributed within the breast
tissue and determining the stage and phase of the breast cancer
(Step S26). Here, the Steps S21-S25 are similar to the
above-mentioned steps and are not detailed.
[0042] For determining the stage and phase of the breast cancer
(Step S26), the distribution, density, shape and composition of the
microcalcification may be taken into consideration. For example,
the more microcalcification distributed within a certain part, the
higher diagnostic probability of malignant tumor; and
microcalcification of irregular shapes, such as linear shape,
radial shape, and fork shape may lead to malignant tumor.
Therefore, clinical practitioners may easily find the location of
microcalcification in the breast ultrasound image by using the
present invention for the stage and phase determination of the
ductal carcinoma in situ and the objective basis for subsequent
adoption of positive treatment or conservative observation.
[0043] The following description describes a specific embodiment of
the present invention used for detecting the microcalcification in
a biological sample mock. The mock composition includes gelatin
(used for simulating the biological tissue), cellulose (used for
simulating the speckle noise in the ultrasound image), Intralipid
(used for simulating the light scattering within the tissue) and HA
particles (used for simulating the microcalcification associated
with malignant breast tumor.
[0044] Refer to FIG. 5, which is an ultrasound image of the mock
tissue according to an embodiment of the present invention, where
the image mode is B mode, the dynamic range is 35 db, and the mock
is fixed in the water. As illustrated, the upper dark region having
no reflection illustrates the water where the mock is placed in,
and the surface of the mock is illustrated at 12 mm in depth. There
are a lot of speckle noises in the mock image masking the signal of
microcalcification. Therefore, due to insufficient contrast in the
image, the location where the microcalcification is present is very
difficult to tell.
[0045] Refer to FIG. 6, which is a photoacoustic ultrasound image
according to an embodiment of the present invention. A
photoacoustic image mode, setting of which is 800 nm in wavelength
and B mode, is adopted for scanning in the same scanning area. The
RF (radio frequency) data obtained from scanning is then processed
with envelope detection to obtain the illustrated result, where the
brightness of the image is expressed in linear scale. As
illustrated in FIG. 6, the surface is illustrated at 12 mm in
depth, and an obvious bright spot, i.e. the microcalcification, is
illustrated at 13 mm in depth.
[0046] Due to weak absorption to 800 nm infrared, both the
peripheral tissue around the microcalcification and water above the
mock have weak photoacoustic signal and display dark in the image;
therefore, it shows strong image contrast between the
microcalcification and the background in the photoacoustic
image.
[0047] Refer to FIG. 7, which illustrates an imaging result of the
microcalcification in the tissue according to one embodiment of the
present invention. FIG. 7 illustrates the superimposed result of
the ultrasound image illustrated in FIG. 5 and the photoacoustic
image illustrated in FIG. 6, wherein the ultrasound image is
displayed in grayscale and the photoacoustic image is display in
red color (pseudo-color). The completely overlapped result of these
two surface signals demonstrates FIG. 5 and FIG. 6 illustrate an
identical cross section. The superimposed image illustrates a
clearer result by showing the structural distribution of the breast
mock of the ultrasound image and the presence of the
microcalcification illustrated in the photoacoustic image.
[0048] To sum up, by acquiring and overlapping a photoacoustic
image of microcalcification and an ultrasonic image of tissue, the
present invention may display microcalcification distribution to
further analyze the phase and stage of breast cancer. The image
acquired by the present invention, in comparison to images acquired
by ultrasonic and X-ray mammography, has advantages in no speckle
noises, higher optical contrast, higher ultrasonic resolution, and
so on. The present invention also has an advantage in safety by
adopting a light source having no ionizing radiation.
[0049] While the invention can be subject to various modifications
and alternative forms, a specific example thereof has been shown in
the drawings and is herein described in detail. It should be
understood, however, that the invention is not to be limited to the
particular form disclosed, but on the contrary, the invention is to
cover all modifications, equivalents, and alternatives falling
within the spirit and scope of the appended claims.
* * * * *